1. Field of the Invention
This invention relates in general to stamping machines, particularly to a device for stamping identifying symbols on steel plates.
2. Description of the Prior Art
In the process of fabricating individual sheets of steel plate from coils of steel, identifying symbols are required to be stamped on each sheet. The stamping operation is preferably performed while the sheet is at room temperature, consequently, a substantial amount of force is required. In addition, it is desirable for the die to be in contact with the plate prior to being struck by the hammer to avoid a double blow.
Stamping devices that place the die in contact with the workpiece prior to the blow are shown in U.S. Pat. Nos. 2,427,358 and 3,608,650. The device of the first patent is unnecessarily complex, and the device of the latter patent requires two air valves and control circuitry. One air valve and system is for restraining the die, and the other air valve and system is for operating the hammer. It is desirable to avoid the dual air control system.